Components that are identifiable as parts of a prefabricated building and are imported as part of a complete or incomplete building kit are generally classified under heading 9406. Generic structural steel sections or profiles that are not dedicated to a specific prefabricated building design are more likely classified under the chapter covering iron and steel products. The key is whether the components are specifically designed and presented for assembly into a prefabricated structure.

In addition to applicable duties — including potential Section 232 exposure for steel-framed units — prefabricated buildings may be subject to state and local building codes, which can affect admissibility for certain end uses. Wooden structures may also require APHIS phytosanitary documentation if they incorporate untreated wood packaging or components. A licensed customs broker familiar with construction imports can help navigate these requirements.